Switch



Mmh 1o, 133s.

P. s. BEAR ErrAl.

SWITCH Filed April 12,

1933 2 sheets-sheet 1 March 10, 1936. P. s. BEAR 'Er Al. 2,033,372

swITcH Filed April 12, 195s 2 sheets-sheet 2 5 f fj?, 4,. Jr 0 l I lPatented- Mar. 10, 1936 UNITED STATES zaai-372 SWITCH Paul S. Bear,Dowag'iac, Mich., and Herbert E.

B ucklen, Elkhart, Ind., assig'nors, by mesne assignments. of one-fourth.to Asaid Bear and three-fourths to said Bucklen Application April 12,1933, Serial No. 665,654

11 Claims.

Our invention relates to switches and the like. The particularembodiment disclosed herein is a gravity operated mercury switch. Theinvention is particularly advantageous to switches of that class but itis not our intention'to confine the invention vto that class of devices,as certain phases of the invention have utility in other classes ofdevices.

Enclosed mercury switches of the gravity operated type have come intowide use for circuit control under conditions where exposed contacts aresubject to deterioration by atmospheric and other influences. Beingenclosed they are less able to dissipate the heat generated `by the flowof current therethrough and particularly the heat evolved as the switchapproaches interruption of the circuit, or as it closes the circuit, andalso during actual interruption. sistance of mercury is relatively highand it is a known fact that as the mercury begins to attenuate onapproaching interruption, a very considerable amount of heat may beevolved.

In devices of this class as heretofore `constructed the conduction ofsuch heat to the seal where the terminals enter the envelope has re-vsulted in opening of the seal or cracking of the envelope. Hence it hasbeen difficult to construct practical switches of this class foranything but small current flow and low wattage.

It is the chief object of our invention to improve the construction andmode of operation of switches of this class to secure greater freedom Efrom injury, particularly by heating.

:3 A further object of the invention is to increase the capacity ofswitches of this class.

According to one phase of our invention, we provide a novel form ofenvelope in place of the glass or rigid insulation heretofore employed.With this construction, construction is facilitated and permanenttightness of the envelope, particularly atv the seal, is more readilymaintained, even under adverse conditions.

According toanother phase of our invention, we provide a separatemercury container of heat resist-ant material, particularly designedforsustaining the localized heat of thearc formed upon interrupting thecircuit.

Another feature of our invention, consists in providing a liquid fillingofinsulating material, which has the important dual function of assist'-ing in extinguishing the arc of interruption and the temperature of thedevice, thereby reducing the concentration of heat upon the seal.

' Further, we provide as an optional form of the invention a metallicenvelope whichis provided with increased heat radiating surface, and,pref- 5 erably, at the same time, is expansible and con# tractible withvariations of internal pressure such as may be caused by heat.

A further improvement resides in the provision of inleads of a novelconstruction designed, 1 among other purposes, to conduct heat morefreely and dissipate the same from the interior of the switch.'

Another important feature of. our invention resides in the constructionof the channels for the mercury, t'o provide a latching in and latchingout effect, for more positive action in opening and closing the circuit.

Another feature of improvement is the provision of a novel character ofsurface of either the walls of the mercury container, the envelope, theelectric terminals, or all such parts as may be in contact with themercury. We have discovered that the friction of the iiow of mercurywith the surface on which it rests, or against which it bears, may begreatly reduced by honeycombing or pitting these surfaces.

It is another important object of our invention to improve the structureof switches of this class, both for greater ease and lower cost' ofconstruction and for greater uniformity in manufacture. Accordingtoknown processesof manufacture` there is Aan'unavoidably large percentageof rejects. Our invention aims to reduce this.

- Among the novel features contributing to this object is theconstruction of the envelope of a material separate and distinct fromthe mercury container. By constructing these parts separately, each maybe designed andconstructed best to perform its-individual purpose or4purposes. For example, the envelope may bemade', inwhole or in part, ofcellulose acetate, "which is easily worked, molded and joined. Themercury container may be made, in whole or in part. of unglazedporcelain, constructed by the wet process or the dry process, or it maybe made of any similar material. y V r The switch may be made up of ametal container, sealed with a molded insert, and a single electrode orinleads employed. 'I'he surfaces of the metal parts in contact with themercury may be treated to give them a' honeycombed or scratchf finish,as by sand blasting, brushing, or .55

the liketo control the friction of flow of the mercury in contacttherewith.

Numerous improvements in detail will be apparent from the followingdetailed description, drawings and claims.

Now in order to acquaint those skilled in the art with the manner ofconstructing and operating the device embodying our invention, we shalldescribe, in conjunction with the accompanying drawings, a specificembodiment of the invention.

In the drawings:

Figure 1 is a horizontal sectional view of a switch embodying` ourinvention;

Figure 2 is a vertical longitudinal section of the same taken on theline 2-2 of Figure 1;

Figure 3 is a view similar to Figure 2, except that the switch has beentilted through a large y angle and is in circuit closing position.

Figure 4 is a horizontal sectional view similar to the view of Figure 1,showing the mercury in the position indicated in Figure 3;

Figure 5 is a transverse cross-sectional View taken on the line 5-5 ofFigure 2;

Figure 6 is a longitudinal horizontal section of the unit like Figure 1,but showing the mercury in position to close the circuit;

Figure 7 is a fragmentary longitudinal sectional view showing a modifiedconstruction of the electrode or inlead;

Figure 8 is a similar view showing another form of electrode or inlead;

Figure 9 is atop plan view of a modified form of switch;

Figure 10 is a vertical longitudinal section taken on the line Ill- I0ofI Figure 9;

Figure 11 is a horizontal longitudinal section of a modified form ofswitch employing a transparent molded envelope and a ceramic mercurycontainer;

Figure 12 is a fragmentary sectional view on the line I2--I2 of Figure11, showing the position of the mercury with respect to the dividingvane;

Figure 13 is a cross-sectional view on the line I3-I3 of Figure 11;

Figure 14 is across-sectional view on the line lll-I4 of Figure 11;

Figure 1'5 is a cross-sectional View on the line Iii-I5 of Figure 11;

Figure 16 is a cross-sectional view on the line IB-IG of Figure 11;

Figure 1'7 is a side elevational View of the inlead employed in thestructure of Figure 11;

Figure 18 is an end View of the inlead shown in Fig. 17;

Figure 19 is a longitudinal vertical section through a modified form ofswitch, showing the ceramic mercury container spaced from the walls ofthe envelope;

Figure 20 isa horizontal longitudinal section of a modified form ofswitch; Figure 21 is a side elevational view of the same;

Figure 22 is a horizontal longitudinal section of another form of switchembodying our invention;

Figure 23 is an enlarged fragmentary elevational view of a honeycombedsurface such as we employ in certain parts of our switch; and

Figure 24 is a sectional view through a globule of mercury resting upona surface such as shown in Figure 23.

Referring first to the switch shown in Figures 1 to 6, this structureincludes a tubular glass envelope I, within which is contained a mercurycontainer, in this case a ceramic such as unglazed porcelain, whichserves to hold the mercury which, in Figure 1, is shown in two globules,namely, 3 and 4, on opposite sides of a partition 5, the forward portionof which partition constitutes a separator 6. A pair of electricalconductors I, 'I generally termed inleads, extend lthrough the wall ofthe envelope I, a seal being formed at 8 about the inleads. The innerends of the inleads l, l are adapted to contact with the globules ofmercury 3, 4 in any of the normal operating positions of the switch. Theinner ends of these inleads rest on the floor of the mercury containeron opposite sides of the separator 6. The mercury container 2, which ispreferably formed of unglazed porcelain, is manufactured separately andis employed as an insert within the envelope. The inleads 'I constitute,in this form of switch, a horizontal portion 9 resting upon the bottomof the mercury container, a diagonal portion I2 extending from thebottom of the container upwardly, and a horizontal portion I3. Both theportions 9 and I3 may engage the adjacent surface of the ceramic insertto hold the same in place, or engagement of either portion with theceramic may be employed for this purpose. The shape of the passagewaysI4, I4 on either side of the separator 6 is such as to produce a gradualconstriction to a central portion of maximum constriction and then anexpansion thereafter in theI direction of flow. This is for the purposeof giving the mercury a latching in and latching out eifect. That is tosay, the tendency of the mercury to remain in circuit closing positionuntil av definite gravity action overcomes the tendency to remainstationary, and the tendency to remain in circuit opening positionuntil, likewise, a gravity action becomes great enough to cause motion,is secured by this construction.

Consider the switch as shown in the position of Fig. 1 with the mercuryglobules 3, 4 back of the separator 6. The partition 5 separates the twobodies of mercury and the enlargement at 6 tends to hold them in place.If, now, the switch as shown in-Figs. 1 and 2 be tilted in a clockwisedirection, as the motion proceeds the righthand end of the switch shownin Figure 2 will begin to tilt downwardly, that is, lie below theleft-hand end and the tendency will be for the mercury bodies 3, 4 topass the separator and join in the space I5 in front of the nose of theseparator 6. However, the necessity for laterally deforming the mercuryto enable it to pass through the constricted portions I4, I4 requires adefinite, though small, force. The tendency, therefore, is for themercury to increase in vertical thickness, that is, to assume a highergravity head by reason of the force required to deform the samelaterally. Then, as soon as the component of gravity, acting upon thebodies 3, 4, has become great enough to force one or the other of thesebodies through its corresponding channel I4, there is a tendency for theflow, after -it isonce initiated, to continue and, in effect,

to overthrow the position which would represent anapproach to stableequilibrium gradually. The necessity for piling up the mercury in irontof the 'most constricted portion gives an excess of operating forcewhich causes this overthrow.

When the switch is to be moved to the opposite position, that is, fromcircuit closing position to circuit opening position, the reverse actionoccurs. The breaking of the circuit is illustrated in Figure 11. I

It is, of course, well recognized that mercury always tends to assume aglobular form, as does any liquid when removed from other inuences, dueto the surface tension. 'I'he surface tension of mercury is quite strongand where the mercury does not wet the contacting surface the surfacetension is important in controlling the shape of the body of mercury.

As the switch is tipped in counter clockwise direction, see for exampleFigure 6, where the body of mercury begins to be forced through thechannels I4, I6, it will r sist deformation but will gradually be forcedin o the channels I4, I4 until, with the building up in vertical heightofv the mercury and suiiicient component of gravity being present, itwill suddenly proceed through the channels i6, I4 and run into thepockets on each side of the partition 5. After the mercury has oncereceded from the position show'n in Figure 6 to the'position shown inFigure 11, it will proceed to a break. 'I'he tendency of the mercury toassume a globular form assists in this break for the reason that as aconsiderable body of mercury forms .beyond the most constricted portionof the channels i4, I4 on each side of the separator 6, the mercurythere tending to assume its globular form pulls upon the mercuryremaining in front of the separator 8 and thereby assists in theseparation of the two portions.

A minor variation in lateral leveling of the switch is relativelyunimportant. However, it is desirable that the switch be leveled uptransversely, so that approximately equal parts of the mercury form thebodies 3, 4 throughout the operation of the switch. 'Tilting of theswitch to an extreme closed position or an extreme open position doesnot alter the circuit controlling relation of such position. That is tosay, in moving the switch from' opento closed position the angularmotion may be extreme but it does not change the circuit conditions.Likewise,'when the switch is tilted toward the open circuit positionandthe mercury is once broken, continued tilting in that direction willnot again close the circuit. l

The mercury container 2, which is formed as a separate body, ispreferably made of porcelain, either by the wet processor the dryprocess.

The wet process gives much greater strength and density and,particularly for the purpose of breaking the arc across the nose of theseparator 6, such formation of the insert is desirable. However, it maybe made by the dry process, which-is considerably cheaper and, undercertain circumstances, equally suitable with the wet process porcelain.l

We have discovered that by the use of unglazed porcelain, sand blastedglass, or, in fact, any such material the surface of which is full ofcellular pockets, herein termed a honeycombed surface, the freedom of owof the mercury on the surface may be greatly increased. We refer toFigures 23 and 24 in explanation of the same, It iswell known that thesurface of unglazed porcelain is irregular and characterized by necellular de pressions or pores, particularly inthe case of dry processporcelain'. Sand blasted glass similarly has fine pits or craters formedin the surface. We have found that a globule of mercury resting on sucha surface can move far more freely than if the surface were smooth anduninterrupted. It appears that the mercury has this freedom on such ahoneycomb surface for two reasons. First, the mercury beingnon-capillary and having such a high surface tension, and failing to wetthe surface on which it rests, tends to rest -only upon the high pointof the surface, the surface tension tending to bridge the low spots.Second, these cells tend to trap air, assuming the surface to be dry,and the mercury rests then partly -upon the high spots and partly uponthe entrapped air. The air thus serves as alubrcant.

In the case of a liquid filling such as we employ in certain-forms ofour invention, the liquid arc extinguishing material tends to wet thesurface of the porcelain or sand blasted glass, and instead of a gasbeing trapped in the pockets such as I5, l5, liquid is trapped thereinand serves as a lubricating medium between the mercury and the surfaceof the body I6 with which it engages. The arc extinguishing liquid fillsthese small pockets, or pits, and is particularly useful in providingliquid directly in contact with both the mercury and the insulation,protecting theI insulation directly from the heat of the arc Iand,byvaporization under the mercury, tending to drive the mercury away andthereby increase the length of and extinguish the arc.

This principle of forming a self-lubricating surface for use inconnection with mercury mayk be employed where a ceramic insert, such asporcelain, may be employed, or if the mercury rests in direct contactwith a glass envelope the surface of the glass with'which the mercury isto contact may be treated, as by sand blasting, to incorporate the largenumber of surface depressions to give the desired honeycomb effect. Anyother material with which the mercury comes in contact in the course ofits operation may be similarly treated, either in whole or in part, in

4order to govern the relative freedom of move- One example of a suitablecompound for use in this connection is trichloro-iluoro-methane.

By making the mercury container and the envelope of separatefparts it-is possible to design each properly to perform its own function,without compromise with respectto the other. Als'o, the tendency forheat to be concentrated upon the seal 8 is reduced. The separator 6,across the nose of which the chief heating eifect 'occurs, may be made aseparate piece but prefer- Y ably is integral with the remainder of thecontainer. By employing a lling of a light insulating and arclextinguishing liquid such as the isa tendency, first, to keep thesurface of the porcelain wet with the arc extinguishing liquid and topreserve it, therefore, against injury by Second, the presence of thearc extinguishing liquid -in the pores of the porcelain tends to give animproved arc extinguishing efhydrocarbon derivatives above mentioned,there.

fect; and, third, the presence of the arc extinlguishing liquid withinthe envelope tends to iii to assist in this equalization of the heat,and may be so formed as to subject them more freely to the coolingeffect of the liquid ller. For example, in Figure 7 we have shown theinleads or electrodes I8 as extending through the seal 8 and thenforming-a loop to approach the position of the channels on each side ofthe separator 6. I'n this way a greater length of the inlead is exposedto the cooling or heat distributing effect of the lling liquid betweenthe portion where heat is received and the sealed portion 8.

In Figure 8 the inlead is shown as comprising an end portion whichengages the bottom of the ceramic insert 2, and then a horizontally eX-tending portion 23 lying above the floor of the insert. In each casethelength of conductor exposed to the cooling effect is therebyincreased.

Also, greater freedom for the flow of the mercury is thereby provided.

The conductors which form the inleads or electrodes may be made ofcopper .with a chromium plating thereupon, o r they may be made of thewell known materials such as iron, or alloys of iron, stainless steel,etc. Preferably, but not necessarily, We make these inleads of a largerdiameter than has been customary heretofore and, by providing thecooling effect [of both the ceramicacross which the inleads extend. andthe lling where it is used, less danger of injury to the seal is caused.

It will be observed that the upper horizontal portion I3 (seeparticularly Figs. 1 and 2) extends in quite intimate contact with thethickened portion at the right of the mercury container 2, hence, if theinlead is subjected to` heating, it tends to equalize with the porcelaininsert 2 before the heat is conducted to the seal 8.

In Figures 9 and 10 we have shown a modification in which the envelopeis formed of cellulose acetate. This material is substantiallytransparent and is of a fairly clear color. It is flexible in thinsection, although of sumcient rigidity q to serve the purpose desired.It may be easily shaped, pressed and molded, particularly when heated toapproximately the temperature of boiling water, and it is readilydissolved in certain solvents such, for example; as acetic anhydride.The envelope may be constructed of sections, which are then joined bywetting the adjacent edges with solvent and pressing them together, orby a suitable cement which contains a solvent, to join adjacent parts.

In the form shown in Figures 9 and 10 the ceramic insert 2 issubstantially like that disclosed in connectionv with Figures 1 to 6.The

envelope I is formed in sections. AThe main body section 25 may be astraight tubular piece with a closed end. In the form shown in Figures 9and 10 we have provided this section'with an expansible portion 26 totake care of pressure arising due to heating `of the filling liquid orgas. It also serves the important function of increasing Ythe coolingarea, particularly where there is a lling of liquid or gas. The neckportion 21 joins the body portion 25 and the seal portion 2B.v

This seal portion maybe made integral with the neck`21 or it may bemade, as shown in Figure 10, cf two separate plates 29, 29 havingsuitable openings or holes therethrough for receiving the shanks of theinleads 1, 1 and for engaging upon opposite sides of the integral flangeformed on `the shank of the inlead as shown in Figures 17 The two plates29, 29 are assembled on and 18. opposite sides of the flange 3l) andthen cemented together orheated and pressed together to cothe partition5 and the side walls.

alesce and form a tight seal. The inner plate 29 may be made integralwith the neck portion 21 if desired. The body` of mercury may beinserted prior to the joining of the neck and body portion or it may beintroduced afterward, as desired. For this purpose a small lling openingis provided in the boss 32 and this opening may then be closed by thescrew 33 which, before being threaded into the opening, is smeared witha cement or solvent to join it to the body of the boss 32. The innerendof the screw 33 may have a projecting portion 34 extending over theedge of the ceramic 2 to hold it in place,

The operationof this form of the device is like that previouslydescribed in connection with Figures 1 to 8. It is to be understood thatwhile glass cannot be satisfactorily formed into a flexible portion suchas 26, nevertheless the glass envelope may be corrugated to increase theheat radiating capacity, particularly where a liquid iiller is employed.

Where the envelope is of a material which might be dissolved by a liquidfilling of a chlorinated hydrocarbon or the like, or alected thereby, weuse as the liquid filling pure Water with suflicient admixture of anon-freezing component, such as alcohol, glycol, or the like, to

maintain the same in fluid condition at all temperatures. ing medium andit also has a high thermal capafCtY.

In Figures 11 to 16 we have shown a modied form of switch employing thecellulose acetate envelope. In this case the envelope is substantiallyrectangular in cross-section, the corners being suitably rounded. Thebody portion of the envelope 35 has a completely closed end at the left,as viewed in Figure 11. The porcelain or ceramic insert 2 is slippedinto the same telescopically and then the neck portion 36 and sealportion 31 are joined to the main body portion 35 with the inleadsl, 1in place. The ceramic in-.

sert 2 is preferably shaped to fill out completely the bottom part ofthe envelope so that the mercury cannot escape into any crevices betweenthe envelope and the ceramic vinsert during shipment or during use.Since the cellulose acetate envelope may be easily softened, either byheat or by solvents, it is comparatively easy to telescope these partstogether sufficiently to make a close t of the envelope with theceramic. A suitable cement may be be inserted between the sideand bottomwalls of the ceramic and the envelope' to iill up any space which mightappear.

In Figure 1,1 the operatonof opening the circuit between the inleads'1,1 isshown. That is to say, the body of mercury I is just moving towardsthe open'position. It will be seen from Figure 12 that the height ofthebody of mercury I0 in advance of the nose of the separator 6 ishigher than that of the portions which have passedthrough lthe mostconstricted part of the passageway. While the mercury has very littlerigidity, itnevertheless resists distortion, and may be considered as aconcrete, definite body of very little strength.

In the sections of Figures 12 to 16, inclusive. the inleads orelectrodes have been omitted for the sake of clearness. In Figure 16 itis assumed that the mercury has been completely divided into itsportions 3, d and these have spread out to minimum thickness to fill thespace between The other views, I2, I3, I4 and I5, show the mercury inthe transitional position illustrated by Figure 1.1.

Water is an excellent arc extinguish on the line of the conductors 1, 1or in any other desired manner.

The anges 30 on the conductors or inleads 1, 1 are preferably secured bywelding, brazing, soldering, or the like, to secure a tight connectionto prevent gas leakage along the surface of the conductor. Asufficiently tight joint may be made by mechanically shrinking the ange30, it

being in the shape of a washer, but it is better' gas-tight union.

While we have described the ceramic insert 2y as tting closely withinthe lower part of vthe envelope, it is to be understood that it is notemential that the parts be in extensive contact. It is desirable toprovide no crevice into which the body of mercury could, in whole or inpart, be lodged. In` Figure 19 we have shown th ceramic insert asprovided with a ange 42 which fits against the inner walls of theenvelope 4U to provide a substantially mercury-tight joint, the otherportions of the ceramic insert 2 being spaced away by projections suchas 43, 43. In this event the space is preferably filled with aninsulating liquid of the type heretofore discussed, to assist intransferring heat from the ceramic material 2 to the walls of theenvelope. 'Ihe seal of the envelope upon the inlead 1 may be made muchas in the case of glass, by fusion and by 4compressing the material ofthe envelope or neck portion 39 upon the inlead 1.

While in the above-forms of our invention we have disclosed theseparator 6 as disposed in such a position as to divide the body ofmercury into two parts for the purpose of breaking the connectionVbetween the inleads, our invention contemplates other means ofperforming this interruption of the circuit, as shown, for example, inFigures 20 and 21. In this construction the inleads 44 extend into oneend of the constricted envelope 45. envelope is made of celluloseacetate, although it may be made of bakelite, or any other moldedmaterial, if desired. The interior surface of the envelope 45 ishoneycombed along the side and bottom walls, as indicated at 46, oneither side of a central portion 41 which is of smooth or flat surface.A body of mercury 48 is adapted to connect the inner ends of the inleads44 and is adapted to extend through the central A restricted portion inbreaking the circuit between said inleads. The inleads are sealed intothe envelope as by means of the plates 29, 29 lying on opposite sides ofthe flanges 30 on the inleads 4,4, and being cemented together. Theseplates may then in turn be cemented to the end of the envelope `45 whichhas a suitable flange for this purpose. At its opposite end the envelope45 has a similar iiange for cementing the closing plate 49 thereto.Obviously, instead of a separate closure plate, one end of the envelopemay be provided with an integral closure.

If the switch sliown in Figure 21 is subjected to tilting so that theright-hand end tilts down, the body of mercury 48 tends to crowd intothe narrower portion, where it meets the two restraining forces, namely,the smooth part of the walls 41 and the constricting eect of these wallsupon the body which body tends to remain as nearly as possible inglobular form. However, as soon as a substantial part of the mercury hasbegun to move beyond the constricted portion, the motion will continueto the point of breakis indicated at 52.

Preferably this ing the connection between the electrodes 44, 44. Uponreverse tilting the action is repeated, that is, there is rst a holdingback'effect and then,

lwhen the mercury does begin to move, it proceeds to an overthrow,thereby accomplishing the latching in and latching out effect heretoforementioned.

In Figure 22 we have illustrated a modiled form of our invention inwhich the envelope is formed of sheet metal such as iron, stainlesssteel, or the like.` The main body of the envelope The seal 53, throughwhich the single inlead or electrode 54 extends, may be a molding ofbakelite o'r the like. The opposite end of the sheet metal body 52 maybe closed by a cap 55 which is secured as by beading, shown at 56, orsoldering or the like, to form a closure. In this case, the conductivecharacter of the envelope 52 eliminates the necessity for one of theinleads and the body of mercury 51; which connects the inlead 54 withthe envelope 52, forms the switching element. The central part of theen'velope 52 is constricted sumciently to give the eect heretoforedescribed, that is, it gives the definite, fullestroke tendency of themercury to proceed to the complete making or breaking of the circuitafter it once starts into motion.

In the forms shown in Figures 20 and 22 the mercury preferably does notfill the cross-section of the narrowest part, although it may do so. If

the mercury fills the narrowest portion of the cross-section, then thegas pressure which is created on one side or the other tends tointroduce a variable, which is generally not desirable. For this reasonthe depth of the envelope in a verticaldirection is made great enoughand the size of the globule of mercury is controlled so as to preventythe filling of the narrowest section by the globule of mercury undernormal operation.

Obviously, a suitable liquid filling for arc ex.

tinguishing and heat dissipating 'purposes may be employed, optionally,in any of the forms to which we have referred.

Where a metal envelope is employed, two inleads and an ungrcundedcircuit may be utilized by inserting the porcelain mercury containerheretofore described. That is to say, the main body of thegenvelope,excepting the seal, may be made of metal or other conductive materialwhere the porcelain' mercury container is used. In such case theenvelope, as well as the leads, should be made of a metal oralloy whichis not subject to amalgamation with the mercury. We contemplate theemployment of other conductive liquids besides mercury.

The separator 6 may extend to the top of the ducting away heat from thepoint of current interruption. It may be made a part of the envelope, ifdesired.

The extension of the partition 5 throughout the entire distance from theseparator 6 to thev end `-Wall of the mercury container is not essenitial where the globules of mercury 3, `4 leave the envelope,particularly for the purpose of concomprising an elongated open toppedreceptacle l having a vertical partition extending along a part .of thelength of the container, inleads extending through the envelope and intothe container upon opposite sides ofthe partition, a

body of mercury in the container, said partition dividing the body ofmercury upon tilting of the envelope, the portion of the partitionadjacent the dividing edge being thickened, said container havingchannels for the mercury, which channels are constricted by thethickened portion of said partition.

3. In a device of the,class described, an elongated cup shaped mercurycontainer having a vertical interrupter partition along a part of thelength of the container, said `partition having a relatively thickforward portion and a relatively thin rear portion to provide restrictedVenturilike spaces between said thick part of the partition and each ofthe side-walls.

4. Ina gravity operated mercury switch, an envelope, a body of mercuryin said envelope, said envelope containing a pair of Venturi-likechannels for the movement of said mercury therein by gravity, and a pairof electrodes each extending into one of said channels.

5. In a gravity operated mercury switch, an envelope, a body of mercuryin said envelope, said envelope containing a pair of Venturi-likechannels for the movement of said mercury thereinby gravity, saidchannels at one end leading into a common pocket and at the other endinto separate pockets, and a pair of electrodes each extending into oneof said channels and remaining in contact with a part of the mercuryuntil after the circuit between them is broken by separation of the bodyof mercury -into two bodies as it ows into the two separate pockets.

6. A mercury switch comprising a casing hav-v ing a pair of inleads, abody of mercury within the casing for establishing and disestablishingcircuit connections between the inleads, and a.

partition of insulation adjacent one end of the casing providing twoconstricted passageways leading from a junction chamber and dividing lthe body of mercury into two separate bodies as the mercury moves fromone end of the casing to the other, the mercury passageways beingconstricted adjacent the free end of the partition and widened beyondthe constricted portion to increase the minimum force required toovercome surface tension in separating of the body of mercuryinto twobodies and to accelerate thek mercury by surface tension when the bodyof` mercury iirst separates into two bodies, the inleads extending intothe two constricted passageways and in engagement with the mercury atthe time of division thereof, whereby the circuit between the'inleads isfirst opened at the point of division of the body of mercury, and thegap in the circuit is increased by the acceleration of the mercury. l

7. A mercury switch, comprising a tubular -outer container composed ofcellulose acetate material, said container having a uid opening at oneend and a sealing portion at the vother end, an open mercury dish insaid container, a closure member extending through said uid opening andengaging said dish, a contact member extending through said sealingportion and having a ange in sealed relation therewith.

8. A mercury switch, comprisingan envelope of metal having insulatedinleads and composing a mercury container, said container having arestricted throat portion, Aand said inleads extending into said throatportion, a body of mercury for connecting'and disconnecting said inleadsdisposed in said container, and a body of an insulating uid fortransferring the heat due to current flow from the mercury and saidinleads to said metal envelope.

9. A mercury switch of the type described, comprising a container havingan enlarged portion and a restricted portion, at least a part of saidenlarged portion being composed of a metal Aand forming an electricalconnection with a body of mercury contained in said switch, and a secondelectrical connection extending into said switch and terminating withinthe restricted portion, said second connection being insulated from saidmetal and adapted to form an electrical circuit with said metal and abody of mercury in said switch when the switch is in proper position.10. In a gravity-operated switch, a container having a Venturi-likechannel of substantially circular Vcross section and forming a path oftravel for mercury, a body of mercury in said container, and anelectrode within said container and centrally positioned within saidVenturi-like channel.

11. In a gravity-operated switch, a container having an electricallyconductive body member and a restricted portion forming a Venturi-likechannel for the path of travel of mercury, a body of mercury within saidcontainer, and an electrode extending into said container in regulatedrelation with respect to said body member, said electrode beingsubstantially centrally positioned adjacent said channel.

PAUL S. BEAR. VHERBERT E. IBUCKLEN.

